Hi Michal, On 10/23/2018 01:23 AM, Michal Hocko wrote: > Hi Shuah, > > On Mon 22-10-18 18:52:53, Uladzislau Rezki wrote: >> On Mon, Oct 22, 2018 at 02:51:42PM +0200, Michal Hocko wrote: >>> Hi, >>> I haven't read through the implementation yet but I have say that I >>> really love this cover letter. It is clear on intetion, it covers design >>> from high level enough to start discussion and provides a very nice >>> testing coverage. Nice work! >>> >>> I also think that we need a better performing vmalloc implementation >>> long term because of the increasing number of kvmalloc users. >>> >>> I just have two mostly workflow specific comments. >>> >>>> A test-suite patch you can find here, it is based on 4.18 kernel. >>>> ftp://vps418301.ovh.net/incoming/0001-mm-vmalloc-stress-test-suite-v4.18.patch >>> >>> Can you fit this stress test into the standard self test machinery? >>> >> If you mean "tools/testing/selftests", then i can fit that as a kernel module. >> But not all the tests i can trigger from kernel module, because 3 of 8 tests >> use __vmalloc_node_range() function that is not marked as EXPORT_SYMBOL. > > Is there any way to conditionally export these internal symbols just for > kselftests? Or is there any other standard way how to test internal > functionality that is not exported to modules? > The way it can be handled is by adding a test module under lib. test_kmod, test_sysctl, test_user_copy etc. There is a corresponding test script e.g selftests/kmod/kmod.sh that loads the module and runs tests. Take a look at lib/test_overflow.c - It is running some vmalloc_node tests test_overflow.c:DEFINE_TEST_ALLOC(vmalloc_node, vfree, 0, 0, 1); test_overflow.c:DEFINE_TEST_ALLOC(kvmalloc_node, kvfree, 0, 1, 1); test_overflow.c: err |= test_kvmalloc_node(NULL); test_overflow.c: err |= test_vmalloc_node(NULL); This module could be extended to tun these stress tests perhaps? I don't see a selftests test script for test_overflow, one could be added. Adding Kees Cook to the thread for input on test_overflow. thanks, -- Shuah
